The present invention relates generally to string instruments, and more particularly, is directed to a string instrument with variable openings.
Most acoustic guitars have a single sound hole provided in the front wall of the hollow body at a location directly below the strings and at a position between the neck and the bridge of the guitar. The sound hole in combination with the hollow body of the guitar functions as a resonating chamber to amplify the sound of the guitar, without any electrical amplification. The sound hole is normally a round hole. Air inside the hollow body of the guitar vibrates as the guitar top or sound board is vibrated by the strings, and the response of the air cavity at different frequencies is characterized, like the rest of the guitar body, by a number of resonance modes at which it responds more strongly. Some sound is radiated by the movement of the air in and out of the sound hole, although the guitar top sound board is the main radiator of sound.
The sound holes in other stringed instruments generally take different shapes. For example, in the violin, f-shaped or s-shaped openings are provided on both sides of the strings.
It is also known to provide guitars with, in addition to, or as an alternative to the round sound hole, multiple smaller sound holes that produce a clearer and brighter sound. These additional sound holes have been provided at the guitar top sound board, the rear board or at the sides of the guitar.
A problem with such arrangements, however, is that the holes in the guitar are fixed in size and shape, and cannot be changed. Therefore, the sound emanating from the guitar cannot easily be changed. Further, the direction of the sound from the holes cannot be changed, and generally, the sound is emitted along an axis of each hole. Also, the holes cannot be selectively closed. Lastly, the holes are not formed as part of the bridge.